The present invention relates to a face-image processing apparatus for determining a state of opening/closing of the eyes by performing an image process.
As a conventional face-image processing apparatus using a template, an apparatus disclosed in, for example, the Unexamined Japanese Patent Application Publication No. Hei.8-175218 is known. The foregoing apparatus incorporate a template producing means for producing a subject template for a person to be detected by sequentially moving a standard-face template determined previously with respect to a photographed image into all directions to perform correlation calculations; and an eye-region detecting means for detecting an eye region of the person to be detected, by performing correlation calculations by using the subject template.
FIG. 12 is a schematic diagram showing the structure of a face-image processing apparatus disclosed in the Unexamined Japanese Patent Application Publication No. Hei.8-175218 and using template matching.
Referring to FIG. 12, reference numeral 1 represents a person to be detected, 2 represents a camera for photographing the person 1 to be detected and 3 represents an image processing apparatus connected to the camera 2 and incorporating an A/D converter, a normalizing circuit and a correlation calculating circuit. Reference numeral 4 represents a memory connected to the image processing apparatus 3 and having a standard template and layout data about elements of the face including the eyes, eyebrows and so forth previously stored therein. Reference numeral 5 represents an ECU connected to the image processing apparatus 3 and serving as an electronic control unit to which a result of the process performed by the image processing apparatus 3 is supplied. Reference numeral 6 represents an alarm unit connected to the ECU 5.
The conventional face-image processing apparatus structured as described above is arranged such that the camera 2 supplies an image of the face of the person 1 to be detected, to the image processing apparatus 3. The image processing apparatus 3 converts the supplied image signal into a digital signal, followed by performing a process for normalizing light and shade, and followed by supplying a result of the process to the ECU 5. The ECU 5 determines a driving state of the person to be detected, in accordance with the result of the process, followed by outputting a control signal to the alarm unit 6 to issue an alarm.
If the face is moved vertically, the positional relationship between the eyes and the eyebrows in the vertical direction is not changed. Therefore, the conventional face-image processing apparatus using the template is able to reliable specify the eye region such that black portions in the upper portions of the region are eyebrows and black portions in the lower portions of the region are the eyes when a region adjacent to the eyes has been detected by using a region adjacent to the subject eyes. If the movement of the face is factored in, matching of the template must be performed by scanning a large range of the image. As a result, a long time is required to complete the correlation calculations.
To achieve the foregoing problem, an object of the present invention is to obtain a face-image processing apparatus which is capable of specifying the eye region by raising the processing speed and determining opening/closing of the eyes.
According to the present invention, there is provided a face-image processing apparatus comprising: image input means for inputting an image of the face; a nostril-region extracting means for extracting a binarized nostril region from the input image of the face; an eye-region extracting means for extracting a binarized eye region from the image of the face by using the binarized nostril region extracted by the nostril-region extracting means as a reference point; and opening/closing determining means for determining opening/closing of the eyes in accordance with the binarized eye region extracted by the eye-region extracting means.
The nostril-region extracting means extracts a nostril region at a predetermined point at which the retrieval is started by sequentially and spirally retrieving a portion surrounding a retrieval start point.
The apparatus further comprises a memory for storing one frame of the image of the face input by the image input means, wherein the image of the face in the quantity of one frame is used in a process for extracting the nostril region which is performed by the nostril-region extracting means and a process for determining opening/closing of the eyes which is performed by the opening/closing determining means.
The point at which the retrieval is started by the nostril-region extracting means is the position of a center of gravity calculated from the nostril region of the image of the face in the previous frame.
The point at which the retrieval is started by the nostril-region extracting means consists of two positions apart from each other for the same distance from a peak position of a projected histogram of the image of the face in a horizontal direction of the image of the face.